Textbook 4A. 13

[Kaitlin Joya 1I]

A constant-volume calorimeter was calibrated by carrying out a reaction known to release 5.50 kJ of heat in a 0.200 L of solution in the calorimeter (q = -3.50 kJ), resulting in a temperature rise of 7.32 C. In a subsequent experiment, 100.0 mL of 0.200 M HBr (aq) and 100.0 m: of 0.200 KOH (aq) have mixed in the same calorimeter and the temperature rose by 2.49 C. What is the change in the internal energy of the reaction mixture as a result of the neutralization reaction?

Why can the molarities of the mixtures be disregarded for these types of problems? Or are there situation where we have to use them?

[MattDixon3A]

For calorimeters, we only really have to look at the heat capacity, which we can solve by dividing the released heat by the change in temperature. Heat capacity is a quality that describes the amount of energy required to raise temperature by 1 degree Celsius. We can then multiply this value by the temperature raised in the subsequent experiment to find the expended energy. This is why we do not need to worry about the masses/molarities of the substances for these types of problems